The present invention relates to a non-contact type displacement sensor, which does not suffer from mechanical friction slide.
The present sensor can be utilized, for instance, as the sensor which converts the displacement of an acceleration pedal of a vehicle, and control the fuel injection or a throttle valve of an engine according to the displacement of said pedal. The fine control of the fuel injection depending upon the displacement of the pedal is important to keep clean exhaust gas from an engine, thus the device for converting the displacement of the pedal to the electrical output signal has been requested.
A prior displacement sensor utilizes a potentiometer (P) energized by the direct current (DC) power source (DC) as shown in FIG. 1. In FIG. 1, the movable contact (p) slides on the resistance surface according to the displacement to be sensed, and thus an electrical voltage proportional to said displacement is obtained between the movable contact (p) and the ground (E).
However, the prior displacement sensor shown in FIG. 1 has the disadvantage that the resistance surface of a potentiometer undergoes heavy wear, and the life time of the potentiometer is not long because of the frictional slide of the movable contact on the resistance surface. Then, the life time of the sensor itself must be rather short.